Pattern matching for JavaScript" class="reference-link"> Pattern matching for JavaScript

Usage

• Install via npm: npm install z
• Require z in your code and use the matches function: const { matches } = require('z')

Avaiable Patterns

• Matches by value: (x = 1) =>, (x = null) =>, (x = 'true') =>
• Matches by object or array: (x = {a: 1}) =>, (x = [1, 2]) =>
• Matches by type: (x = String) =>, (x = Boolean) =>
• Matches by instance: (x = Date) =>, (x = Person) =>
• Matches by splitting array into elements and tail (head, tail) => , (a, b, c, tail) =>, etc…

Examples

• Example: Matches by Object property
  ```javascript
  const { matches } = require(‘z’)

const person = { name: ‘Maria’ }
matches(person)(
(x = { name: ‘John’ }) => console.log(‘John you are not welcome!’),
(x) => console.log(Hey ${x.name}, you are welcome!)
)

//output: Hey Maria, you are welcome!

- **Example:** Matches by type or instances
```javascript
const { matches } = require('z')
const result = matches(1)(
  (x = 2)      => 'number 2 is the best!!!',
  (x = Number) => `number ${x} is not that good`,
  (x = Date)   => 'blaa.. dates are awful!'
)
console.log(result) // output: number 1 is not that good

• Example: matches Array content

To match array content you need create multiple arguments for the match function, such as (a, b, c, tail) => {} , then each variable match each item from array. Note: last variable contains all remaining array items, formally named tail. Examples:
```javascript
const { matches } = require(‘z’)

matches([1, 2, 3, 4, 5])(
(a, b, c, tail) => ‘a = 1, b = 2, c = 3, tail = [4, 5]’
)

matches([1, 2])(
(a, tail) => ‘a = 1, b = [2]’
)

matches([1])(
(a, b, tail) => ‘Will not match here’,
(a = 2, tail = []) => ‘Will not match here’,
(a = 1, tail = []) => ‘Will match here, tail = []’
)

- **Example:** Powerful recursive code which will remove sequential repeated items from Array.
> Can be mind blowing if it’s the first time you meet pattern matching, but you are gonna understand it!
```javascript
const { matches } = require('z')
const compress = (numbers) => {
  return matches(numbers)(
    (x, y, xs) => x === y
      ? compress([x].concat(xs))
      : [x].concat(compress([y].concat(xs))),
    (x, [y]) => x === y // stopping condition
      ? [x]
      : [x, y],
    x => x
  )
}
compress([1, 1, 2, 3, 4, 4, 4]) //output: [1, 2, 3, 4]

License

Apache 2.0